diff --git a/infer/lib/java/BUCK b/infer/lib/java/BUCK
new file mode 100644
index 000000000..1584fade7
--- /dev/null
+++ b/infer/lib/java/BUCK
@@ -0,0 +1,7 @@
+prebuilt_jar(
+    name = 'models',
+    binary_jar = 'models.jar',
+    visibility = [
+        'PUBLIC'
+    ]
+)
diff --git a/infer/models/java/src/android/database/Cursor.java b/infer/models/java/src/android/database/Cursor.java
index 4a0ac5272..2f364421f 100644
--- a/infer/models/java/src/android/database/Cursor.java
+++ b/infer/models/java/src/android/database/Cursor.java
@@ -9,6 +9,7 @@ package android.database;
 import java.io.Closeable;
 
 import com.facebook.infer.models.InferUndefined;
+import com.facebook.infer.models.InferBuiltins;
 
 import android.database.sqlite.SQLiteCursor;
 
@@ -27,7 +28,7 @@ public class Cursor implements Closeable {
 
     public int getColumnIndex(String columnName) {
       int index = InferUndefined.int_undefined();
-      while (index < -1) {}
+      InferBuiltins.assume(index < -1);
       return index;
     }
 
diff --git a/infer/models/java/src/com/facebook/infer/models/InferBuiltins.java b/infer/models/java/src/com/facebook/infer/models/InferBuiltins.java
index be26d6445..165486774 100644
--- a/infer/models/java/src/com/facebook/infer/models/InferBuiltins.java
+++ b/infer/models/java/src/com/facebook/infer/models/InferBuiltins.java
@@ -8,24 +8,20 @@ package com.facebook.infer.models;
 
 public class InferBuiltins {
 
-    public static void __set_file_attribute(Object o) {
-    }
+    public native static void __set_file_attribute(Object o);
 
-    public static void __set_mem_attribute(Object o) {
-    }
+    public native static void __set_mem_attribute(Object o);
 
-    public static void __set_lock_attribute(Object o) {
-    }
+    public native static void __set_lock_attribute(Object o);
 
-    public static void _exit() {
-    }
+    public native static void _exit();
+
+    private native static void __infer_assume(boolean condition);
 
     public static void assume(boolean condition) {
-      while (!condition) {}
+      __infer_assume(condition);
     }
 
-    public static String __split_get_nth(String s, String sep, int n) {
-        return null;
-    }
+    public native static String __split_get_nth(String s, String sep, int n);
 
 }
diff --git a/infer/models/java/src/junit/framework/Assert.java b/infer/models/java/src/junit/framework/Assert.java
index 648cdb801..1bf1b5510 100644
--- a/infer/models/java/src/junit/framework/Assert.java
+++ b/infer/models/java/src/junit/framework/Assert.java
@@ -5,29 +5,24 @@
 
 package junit.framework;
 
-public class Assert {
+import com.facebook.infer.models.InferBuiltins;
 
-    public static void assume(boolean condition) {
-        if (!condition) {
-            while (true) {
-            }
-        }
-    }
+public class Assert {
 
     public static void assertTrue(boolean condition) {
-        assume(condition);
+        InferBuiltins.assume(condition);
     }
 
     public static void assertTrue(String message, boolean condition) {
-        assume(condition);
+        InferBuiltins.assume(condition);
     }
 
     public static void assertFalse(boolean condition) {
-        assume(!condition);
+        InferBuiltins.assume(!condition);
     }
 
     public static void assertFalse(String message, boolean condition) {
-        assume(!condition);
+        InferBuiltins.assume(!condition);
     }
 
 }
diff --git a/infer/src/backend/symExec.ml b/infer/src/backend/symExec.ml
index 006847e68..a078bc68a 100644
--- a/infer/src/backend/symExec.ml
+++ b/infer/src/backend/symExec.ml
@@ -2117,13 +2117,14 @@ module ModelBuiltins = struct
     | _ -> raise (Exceptions.Wrong_argument_number (try assert false with Assert_failure x -> x))
 
   (* forces the expression passed as parameter to be assumed true at the point where this
-  builtin is called *)
+  builtin is called, blocks if this causes an inconsistency *)
   let execute___infer_assume
       cfg pdesc instr tenv prop path ret_ids args callee_pname loc: Builtin.ret_typ =
     match args with
     | [(lexp, typ)] ->
         let prop_assume = Prop.conjoin_eq lexp (Sil.exp_bool true) prop in
-        [(prop_assume, path)]
+        if Prover.check_inconsistency prop_assume then execute_diverge prop_assume path
+        else [(prop_assume, path)]
     | _ -> raise (Exceptions.Wrong_argument_number (try assert false with Assert_failure x -> x))
 
   (* creates a named error state *)
diff --git a/infer/src/java/jTrans.ml b/infer/src/java/jTrans.ml
index d0da27735..f978b0c74 100644
--- a/infer/src/java/jTrans.ml
+++ b/infer/src/java/jTrans.ml
@@ -632,8 +632,8 @@ let method_invocation context loc pc var_opt cn ms sil_obj_opt expr_list invoke_
       init
       expr_list in
   let callee_procname =
-    if JBasics.cn_equal cn JConfig.infer_builtins_cl then
-      Procname.from_string (JBasics.ms_name ms)
+    let proc = Procname.from_string (JBasics.ms_name ms) in
+    if JBasics.cn_equal cn JConfig.infer_builtins_cl && SymExec.function_is_builtin proc then proc
     else Cfg.Procdesc.get_proc_name callee_procdesc in
   let call_idl, call_instrs =
     let callee_fun = Sil.Const (Sil.Cfun callee_procname) in
diff --git a/infer/tests/Makefile b/infer/tests/Makefile
index 5f3af6447..b6d9fe536 100644
--- a/infer/tests/Makefile
+++ b/infer/tests/Makefile
@@ -1,5 +1,6 @@
 
 ANNOTATIONS_JAR = ../annotations/annotations.jar
+MODELS_JAR = ../lib/java/models.jar
 JACKSON_JAR = ../../dependencies/java/jackson/jackson-2.2.3.jar
 ANDROID_JAR = ../lib/java/android/android-19.jar
 GUAVA_JAR = ../../dependencies/java/guava/guava-10.0.1-fork.jar
@@ -16,7 +17,7 @@ TRACING_CMD = $(INFERJ) -o $(TRACING_OUT) -a tracing $(TRACING_JAVAC_CMD)
 INFER_OUT = infer_out
 INFER_REPORT = $(INFER_OUT)/report.csv
 INFER_SOURCES = $(shell find codetoanalyze/java/infer -name "*.java")
-INFER_JAVAC_CMD = javac -cp $(JACKSON_JAR):$(ANDROID_JAR) $(INFER_SOURCES)
+INFER_JAVAC_CMD = javac -cp $(JACKSON_JAR):$(ANDROID_JAR):$(MODELS_JAR) $(INFER_SOURCES)
 INFER_CMD = $(INFERJ) -o $(INFER_OUT) -a infer $(INFER_JAVAC_CMD)
 
 ERADICATE_OUT = eradicate_out
diff --git a/infer/tests/codetoanalyze/java/infer/BUCK b/infer/tests/codetoanalyze/java/infer/BUCK
index 4dd3957ff..e3eb9f763 100644
--- a/infer/tests/codetoanalyze/java/infer/BUCK
+++ b/infer/tests/codetoanalyze/java/infer/BUCK
@@ -3,6 +3,7 @@ sources = glob(['**/*.java'])
 dependencies = [
     '//infer/lib/java/android:android',
     '//dependencies/java/jackson:jackson',
+    '//infer/lib/java:models'
 ]
 
 java_library(
diff --git a/infer/tests/codetoanalyze/java/infer/Builtins.java b/infer/tests/codetoanalyze/java/infer/Builtins.java
new file mode 100644
index 000000000..e2e78ebbb
--- /dev/null
+++ b/infer/tests/codetoanalyze/java/infer/Builtins.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2013- Facebook.
+ * All rights reserved.
+ */
+
+package codetoanalyze.java.infer;
+
+import com.facebook.infer.models.InferBuiltins;
+
+public class Builtins {
+
+  void blockError() {
+    Object x = null;
+    InferBuiltins.assume(x != null);
+    x.toString();
+  }
+
+  void doNotBlockError(Object x) {
+    Object y = null;
+    InferBuiltins.assume(x != null);
+    y.toString();
+  }
+
+  void blockErrorIntAssume(Object x) {
+    Object y = null;
+    int i = 0;
+    InferBuiltins.assume(i != 0);
+    y.toString();
+  }
+
+  void causeError(Object x) {
+    InferBuiltins.assume(x == null);
+    x.toString();
+  }
+
+}
diff --git a/infer/tests/codetoanalyze/java/infer/build.xml b/infer/tests/codetoanalyze/java/infer/build.xml
index 97c950a5c..5b85f32dd 100644
--- a/infer/tests/codetoanalyze/java/infer/build.xml
+++ b/infer/tests/codetoanalyze/java/infer/build.xml
@@ -8,7 +8,8 @@
         <mkdir dir="ant_out"/>
         <javac srcdir="." destdir="ant_out" includeantruntime="false">
             <bootclasspath>
-                <pathelement location="../../../../lib/java/android/android-19.jar"/>
+              <pathelement location="../../../../lib/java/android/android-19.jar"/>
+              <pathelement location="../../../../lib/java/models.jar"/>
             </bootclasspath>
             <classpath>
               <pathelement location="../../../dependencies/java/jackson/jackson-2.2.3.jar"/>
diff --git a/infer/tests/endtoend/java/infer/BuiltinsTest.java b/infer/tests/endtoend/java/infer/BuiltinsTest.java
new file mode 100644
index 000000000..e7f07a619
--- /dev/null
+++ b/infer/tests/endtoend/java/infer/BuiltinsTest.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2013- Facebook.
+ * All rights reserved.
+ */
+
+package endtoend.java.infer;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static utils.matchers.ResultContainsExactly.containsExactly;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.IOException;
+
+import utils.InferException;
+import utils.InferResults;
+
+public class BuiltinsTest {
+
+  public static final String SOURCE_FILE =
+      "infer/tests/codetoanalyze/java/infer/Builtins.java";
+
+  public static final String NULL_DEREFERENCE = "NULL_DEREFERENCE";
+
+  private static InferResults inferResults;
+
+  @BeforeClass
+  public static void loadResults() throws InterruptedException, IOException {
+    inferResults = InferResults.loadInferResults(
+        BuiltinsTest.class,
+        SOURCE_FILE);
+  }
+
+  @Test
+  public void matchErrors()
+      throws IOException, InterruptedException, InferException {
+    String[] methods = {
+      "doNotBlockError",
+      "causeError"
+    };
+     assertThat(
+        "Results should contain " + NULL_DEREFERENCE,
+        inferResults,
+        containsExactly(
+            NULL_DEREFERENCE,
+            SOURCE_FILE,
+            methods
+        )
+    );
+  }
+
+}
diff --git a/infer/tests/utils/InferRunner.java b/infer/tests/utils/InferRunner.java
index 8b3018c54..8cd92dac1 100644
--- a/infer/tests/utils/InferRunner.java
+++ b/infer/tests/utils/InferRunner.java
@@ -42,6 +42,7 @@ public class InferRunner {
       "/infer/lib/java/android/android-19.jar";
 
   private static final String[] LIBRARIES = {
+      "/infer/lib/java/models.jar",
       "/infer/annotations/annotations.jar",
       "/dependencies/java/guava/guava-10.0.1-fork.jar",
       "/dependencies/java/jackson/jackson-2.2.3.jar",